Security forces are on a high state of alert in Nigeria ahead of Friday Muslim prayers. Days of violence in Africa's most populous nation heighten security concerns.

Security forces are patrolling major cities in Nigeria amid fears of fresh violence. Revenge attacks against Muslims in the predominantly Christian south have prompted fears of another round of violence in the Muslim-dominated north Friday.

Friday is the Muslim day of prayer and often had provided a rallying point for Muslim violence in Nigeria.

At least 120 people have been killed in four days of fighting between Muslims and Christians. Religious violence in one part of the country often sparks reprisal killings elsewhere.

The governors of Plateau in the north and Lagos in the south have spoken about plans to foment religious violence in their domain.

"We have taken adequate measures, the inspector general of police has taken adequate measures to ensure that we do not have any violence tomorrow," said Haz Iwendi, spokesman for the Nigerian police. "The inspector general of police has directed the commissioners of police to do a show of force around the various states and that's going on now. It is to demonstrate our resolve to deal decisively with anyone that makes trouble before or after the mosque."

But the police official observed that until Nigerians learn to tolerate one another, there is very little the security forces can do to stop frequent religious attacks.

"Well, the only thing we can talk about long term solution is for Nigerians to learn to live together as brothers," he said. "That this country belongs to all of us and that we all have a stake in this country."

Religious and secular leaders say uncertainty over Nigeria's political future is stoking ethnic and religious tensions.